Early ovulation with only one follicle on Gonal F

For my first IUI, we did letrozole, and cd10 I had only one mature follicle. I got a positive opk cd10 before I could do a trigger, so we did IUI cd11-BFN. This cycle, I did 100 units of Gonal F, and at my ultrasound CD7, I had only one follicle but it was ready to trigger! We’re doing IUI tomorrow, but I’m wondering if my early ovulation is preventing me from having more than one follicle develop. Has anyone had a similar experience? Has anyone had more success on a different protocol? My AMH is .7, but because I’m 32, my doctor says she’s not concerned.